Sealing apparatus for electron tubes



Oct. 1, 1957 E. F. NICKL 2,807,913

I SEALING APPARATUS FOR ELECTRON TUBES Filed Dec. 10, 1954 Z'SheetS-Sheet 1 INVENTOR. EDWIN E NIEKI.

Oct. 1, 1957 E. F. NlCKL 2,807,913 I SEALING APPARATUS FOR ELECTRON TUBES Filed Dec. l0,' 1954 2 Sheets-Sheet 2 4 INVENTOR: J3 EDWIN F. NIEKL I r 'mvi/ 2,807,913- r SEALING APPARATUS F'OR-ELECTRON'TUBES.

EdwimFrancis'Ni ckl; West Caldwell,-N. J., assignor' to:

Radio Corporation of America; a' corporation of Dela-- ware Application December 10, 1954, SerialNo. 474,563

14 Glaiins. (Cl. 49-2) This invention relatestoielectrontube sealing apparatusand' particularly to an improvedpush-down device.

for use in such: apparatus, for producing an improved seal-and'for desirably orienting electrontuhework-pieces.

to be joinedin: the seal.

One type" of sealing apparatus in which the invention finds utility is employed to seal a flat glass stem. of; an' electron" tube mount'assembly, across an open end.

of a tubular glass envelope. The mount assembly includes conducting leads extending from one face off the stem and anelectro'de assembly mounted on the other face. of the'stem and connected, to the conducting leads through the stem.

In sea'lingjthe' stem to the envelope aforementioned, it

is the practice to-manually'insert the electrode assembly into the envelope through the open end thereof until the stemcontacts the open endreferredto. on'complev tion of this manual operation, the resultant loose assemmy, with'th'e stem leads extending,upwardly,.is mounted on' a sealing pin or support fixture of-the sealing apparatus foritransp'ortation' through a, plurality of work stations atiwhiclt sealing fires are directed tothe region of juncturebetweenlthe'stem'and envelope at which a .seal

is to be made;

As'the glass'attheregionvof juncture is softenedlby the sealing fires, it hecomesdisplaced from this region. Dueto a snug fit in which the electrode assembly aforementionedisireceived in the'tubular envelope, the mount assembly is restrained against relative movement withrcspace" to the envelope .so that the glass disc. of the mount assembly fails to follow to recedingisoftened portion of the envelope; 7

This restraint of movement of the mount assembly, while involvingthe difii-culty of aforementioned-is desirable in making a seal with the work pieces inverted,

since otherwise the weightofthe mount assembly would produce an. excessive force on thesealthatmight result in a fall ofthe mount assembly,,including the stem discthereof, into the tubular envelope. While inverted sealing is'accompanied by the difiiculty referredto, such.- sealing has importantladvantages such, for example, as" permitting convenient support of the work pieces--and-dis-- companied' by difiiculty because of variation infllead' I length from-mountassembly to mount assembly. There= fore, a'isimple push-down of the mount assembly by'engaging the free. endsof the leads thereof has not proven satisfactory, since'by this practice variations in lead length. arereflected in the longitudinal dimensions of the sealed structures.

Accordingly, it is an object of the invention to providean improved apparatus for sealing an' electron tube mount. assembly across. the open end of a tubular envelope.

2,807,913 Patented Oct. 1, 1957 adapted to'engage the free ends of leads extending from" oneface-of: anelectron tube stem and to move said stem' a predetermined distanceindependently'of the length of such leads, whereby a plurality'of stems having leads'of variable length are'moved a-uniform distance for improved sealsand for uniformity of structures-sealed by the apparatus.

Another aimof the invention is to provide 'an improved push-down device for a' sealing apparatus that is adapted to floatingly engage the free ends of stem leads of a loosely assembled mount and envelope structure, and to impart a thrust of predetermined magnitude to the leads only. after such engagement has been effected, for establishinga desired=engagement between the stem and'envelope for an improved seal and for assuring uniformity in: length of a plurality of structures so sealed.

A further object is to provide sealing apparatus including' a p ush-down device having independent means for accomplishing a floatingengagem'ent with 'a' Work piece to be pushed down and for imparting a thrust tothe workpiece only after such engagement, causing a movement thereof of predetermined magnitude;

' Further objects and features-of the invention willbecome apparent as-the present description proceeds.

Referring now to the appended drawing for a detailed consideration'of an apparatus embodying the invention, Figure 1* shows an elevation partly in section of a push-down device according to the invention;-

Figure 2 is a top view of the device shown in Figure 1; Figure 3 is a sectional view taken along the line 3-3 of Figure 1;

Figure 4 isa view in cross-section taken along the line 4"4of Figure 3; v

, Figurefishows an elevation partlyin section of a seal ing'apparatus' according to the invention'and with which partly in sectiontakenalong the device accordingto the invention, and in Figures 5 and 6; there" are shown a portion of a turret of a sealing apparatuswith" which the push-down device is adapted to be advantageously-employed, as well as common actuating=mcansforthe push-'downdevice and the sealingapp'a-ratus;

' The turret Referring-first to Figure 5, a sealing apparatus embodying the invention includes a movable support compris-- ingeas turret--10, supported on a spindle, not shown, for

intermittent rotation thereon. The periphery of the turret includes a plurality ofsleeves ll-oneof which is showna Supported-in sleeves 11 are a fixtures- 12i ing13:

pluralityof support intermittent rotationof turret 10 is provided by a'first power transfer means'comprising a drum cam 'l4'having; a track 15 defined by two raised sunface portions'lti, 17

asshowninFigure 6. The track 15'l1as an entrance portion 18-into-which aroller pin 19 fixed to the undersideof i turret 10,- is adapted to enter on rotation'of drum 14in" the direction' indicatedby the arrow. The track 15- also.

in length of a plurality one of which is shown, rotatable on bear-' has an exit portion 20, from which another roller pin 21, also fixed to the uderside of turret 10, is adapted to leave the track. The track is so shaped that during an appreciable portion of a cycle of rotation of drum 14, the pin 19 as well as turret are held against movement by. a portion of track extending normally to the axis of drum 14. This portion may include an arc of 270. The track has another portion that has a dimensional component extending axially of drum 14. This portion may extend through an arc of 90 to the exit end 20. When pin 19 is engaged by this last named portion of the track, the pin 19 is caused to follow the track and impart a rotating movement to turret 10. The dmm 14 is fixedly mounted on a shaft 22, which is connected to a power source, not shown, for rotation at a constant rate.

The aforementioned rotating movement of turret 10 is of a magnitude to carry support fixture 12 from one sealing position to another. At one of such sealing positions, the support fixture 12 is disposed directly below lever member 23 which is a movable member of a pushdown device to be described. In this position, work pieces comprising a tubular glass envelope 24 having an exhaust tubulation 25 received in the fixture 12, assembly ncludin g a glass disc 26 resting on the upper open end of envelope 24, leads 27 extending upwardly from the glass disc and electrode assembly 28 received in envelope 24, are adjacent burner 29, for heating a contacting region of the disc 26 and the envelope 24. On initially arriving at theposition indicated, the position of the lever member 23 is as shown in Figure l, with a fiat underface thereof directly above the free ends of leads 27. For uniformly heating the region to be sealed, the support fixture 12 is provided with a pulley 30 engaged by a belt 31 which is connected to a power source, not shown, for rotating the support fixture and the work pieces thereon.

The support fixture 12 includes an inner sleeve 32 for supporting the work pieces aforementioned. This sleeve engages a track 33 for raising and lowering the work pieces in accordance with the requirements of some of the work stations of the apparatus.

The push-down device Referring now to the push-down device according to the invention, it will be noted from Figure 1 that this includes an outer sleeve 34 fixed to a bracket adjustably fixed to a rod 36 by means of a clamp 37. Rod 36 in turn is fixed to a clamp 38 by means of a screw 39. Adjacent the lower end of outer sleeve 34 is an inner collar 40 fixed to sleeve 34 by screw 41.

Within sleeve 34 is disposed an inner sleeve 42 for vertical movement therein. The inner sleeve is urged upwardly by an expansion spring 43 bearing on collar 40 and on a shoulder 44 formed on inner sleeve 42. The inner sleeve referred to is provided with a depression or keyward 45 extending longitudinally of the sleeve and serving to engage a key 46 fixedly wedged into an opening in bracket 35 for restraining rotation of sleeve 42 with respect to the outer sleeve 34 for a purpose to be described. The lever member 23 is pivotally supported on a tab 47 extending downwardly from the inner sleeve The lever member 23 comprises a structure including a shank 48 having a curved upper surface 49, an arm 50 extending laterally from shank 48, and a flat plate 51 fixed to arm 50. pin 52 on a horizontal axis. The pin referred to engages a lower portion of shank 48 and extends normal to the direction of curvature of shank surface 49. The plate 51 has an undersurface for engaging the free ends of leads 27 of a mount assembly work piece.

The inner sleeve 42 has an upper portion 53 as shown in Figure 4, of reduced wall thickness. This reduction in wall thickness provides a shoulder 54 having a function to be described. Embracing the portion 53 of the and a mount 7 35. Bracket 35 is The lever member 23 is pivoted on a inner sleeve, is a yoke 55 having an integral arm 56 and supporting two shoes 57, 58. Each shoe includes a cylindrical shank portion 59 and a rectangular head portion 60 of appreciably larger transverse extent than the shank portion. The cylindrical shanks of the shoes are snugly received in opposite openings 61, in yoke 55, one of which is shown in Figure 1. The shoes referred to are spaced from each other to permit the thinned down portion 53 of inner sleeve 42 to extend therebetween, as shown in Figures 3 and 4.

The yoke 55 is pivoted on a pin 62 supported in brackets 63, 64 fixed to bracket 35. The integral arm 56 of the yoke extends upwardly and is connected to a link 65 by means of a pin 66. The link 65 is connected through a sleeve 67 to a second power transfer means comprising piston 68 extending into a pneumatic cylinder 69, as shown in Figure l. The cylinder 69 is supported by a standard 70 fixed to bracket 35. From the foregoing, it will be seen that an extending movement of piston 68 will cause the yoke 55 to rotate on pin 62 in a counterclockwise direction. To limit the magnitude of such rotation an adjustable screw 71 is mounted adjacent the end of yoke 55 remote from arm 56 and abuts against a stop 72 at the end of a desired rotary movement of yoke 55.

The aforementioned spring 43 urging the inner sleeve 42 upward causes the shoulder 54 to engage the lower surfaces of the rectangular heads 60 of the shoes 57, 58. Therefore, when the yoke 55 is caused to rotate in a counterclockwise direction as aforementioned, the shoes referred to are caused to bear downwardly on the shoulder 54 thereby causing the inner sleeve to move downward 1y through a distance determined by adjustable screw 71, for a purpose to be described.

A rod 73 is positioned within the inner sleeve for vertical movement therein. Relative rotation between the rod and sleeve referred to is restrained by a pin 74 extending through the rod 73 and through oppositely disposed slots 75, 76 in the inner sleeve 42. The slots referred to extend axially of the sleeve to permit relative vertical movement between the rod 73 and sleeve 42. The lower end of the rod 73 is provided with a surface 77 having a curvature similar to that of surface 49 of the shank 48 and extending in the same direction. Since the shank 48 is pivoted to tab 47 fixed to sleeve 42 and since relative rotation of sleeve 42 and rod 73 is restrained by pin 74, the unidirectional extent of the curvatures of surfaces 49 and 77 is preserved, for a purpose that will appear clearly in the following.

Therod 73 is fixed to a third power transfer means comprising a piston 78 by means of a sleeve 79 having a cross arm 80. The piston 78 extends into a pneumatic cylinder 81 supported on side plates 82, 83 fixed to bracket 35, as shown in Figures 1 and 2. Compression springs 84, 85 engaging opposite ends of cross-arm S0 and a bracket fixed to the upper end of cylinder 81, as viewed in Figure I, serve to urge the rod 73 upwardly. It will be noted from the foregoing that an extending movement of the piston 78 from the cylinder 81, will cause the rod 73 to move downwardly.

The magnitude of such downward movement is determined by the distance separating the curved surfaces 49, 77 and the distance between a nut 86 threaded to the thinned down portion 53 of the inner sleeve 42, and the upper surfaces of shoes 57, 58 as shown in Figure 4. Thus, downward movement of rod 73 first causes its lower surface to engage the upper surface of shank 48 and lock the lever 23 against rotation. Since the shank is pivoted to tab 47 fixed to inner sleeve 42, further downward movement of the rod after such engagement exerts a downward force on sleeve 42 to cause the latter to move downwardly. The magnitude of downward movement of the sleeve 42, however, is effectively stopped when the nut 86 engages the shoes 57, 58 and the yoke is restrained fromrotation; by engagement betweenzscrew 71,thereon. and-the'stop 72. Atlocknut 86a serves to lock-the nut.

86. in desired position.

The 'common" actuating means A common means is provided forcontrolling. the intermittent movements of-the turntable or turret.10..and the push-down device described herein. This means comprises the shaft 22 shown-in- Figure 5 to which arerfixed. the drum 14 for imparting intermittentmovements to the.

is pivotally mounted intermediateits ends on a pin 93.

fixed to a standard 94 mounted on the base.95 ofthe sealing apparatus.

It willbe seen'fromthepositions. ofthe track. 155 on drum l4rand the cam 87, as shown in Figures. 5. and.6, that .pin 19 of the turntablehas justenteredthe portion of track-15 that extends normal to theaxis of the drum, and. that cam follower 89 is approachingtheraiseddwellon cam.87.' Continued rotation .of shaft 22through an arc of 270 serves to hold the turntable stationary, and tobringthe.raiseddwell on cam 87 intov engagement with cam follower 891. In approaching theraised dwellafore: mentioned, thelever 88 isrotated, on pin 93 in. a clock: wise:direction. Such rotation causes the downwardly ex-.

tendingportion 91 of thezlever to. applya downward pres sure tov valvepin 91, which-resultsrin an opening of .valve.

92, "to permit communication between aconduit 95 con-. nectedto a sourceofair under pressure notshown, and a conduit 96 connectedto pneumaticcylinder 69.

The consequent build-up in air pressure in. cylinder 69 causes the piston 68 to move to an extended position. Such movement of the piston imparts rotation to pin, 62 in a counterclockwise direction as viewed in Figure 1, through link 65 and arm 56. Fixed to pin 62 is a lever 97 having an adjustable screw 93 locked in position by a nut 99, and a rotatable with the pin 62. Rotation of the lever 97 "in a counterclockwise direction causes an end of screw 98' to engage a lever 100 pivoted on a pin 101 and to swing the lever to the left as viewed in Figure 1. Such movement of the lever causes it to depress a. pin 192 urged to outwardly extend, .by means not shown, from an air valve, 103, shown in Figure 2, for opening the valve 103 to provide. communication between an air conduit 104connected to air conduit 96, and air conduit 105, connectedto'the air cylinder 81. Air valve 103 may be sim-. ilar to air valve 92 abovereferred to. Air cylinder 81 is thus energized, causing extension therefrom of piston 7 Sfor-a push-down operation.

To facilitate a'smooth performance of the aforementi'oned several operations of;the pistons 68and 78, fluid flow control valves'1ti6 and 107, shown schematically in'Fi'gure 1, are disposed across conduits 96 and 105 respectively. These control valves are a form of needle valvethat may be very accurately screw adjusted to provide'any desired rate of fluid flow. Valves of this type are well known and are not believed to require further description herein.

Adjustments of the push-down device Certain adjustments of the apparatus are required to accommodate it to" the dimensions of the work pieces processedthereby. In the instant example, the work pieces comprise a tubular glass envelope anda mount assemblyintended to constitute, when sealed together, a subminiature-type of electron tube.

One.v of the. adjustments is made. to. provide. desired clearance between the plate 51 of the push-down device and.the.'leads 27 carried. by. support fixture. 12, during movementofthe. support fixture to aposition directly below the plate.

the plateabout one-eight of an inch above .the leads.

27 vary within atolerance of one=sixteenth of' an inch from work piece to work piece.

Topermit a desired magnitudeof descent of'the. plate 51 to fioatingly engage theleads 27, screw 71*is adjusted.

so as to be spaced slightly more, than-one quarter inch from thestop member 72, to allow the shoes 57 and SS'engaged'by an intermediate portion of the yoke 'to move downwardly abouta quarter of an inch for lowering the. lever 23'into a floating or forceless engagement with leads;-

Adjustment is also necessary of'the magnitude of the downward thrust of the push-down device after the aforementioned floating engagement has been effected and, after the lever 23 is locked against rotation, as will appear more,

clearly from the following description of. the operation of the apparatus. This-adjustment is made-by turning nut 86, as shown in Figure 4, on the thinned down portion of inner sleeve 42.v to provide adesired spacing be tween thelower side of the nut and the upper sides. of

shoes 57, 58; This spacing, in the example under. consideration, is about 50 mils.

It is also necessary that the positions to which the inner sleeve 42 andithe rod 73 are urged by springs 43, 84 and 35, be such as to separate the curved surfaces 77, 49; to permit a floating engagement as aforementioned between the lever 23 and a work piece .to be pushed down. It willbe noted that a stop to upward movement of the sleeve 42 is provided by. the piston 68when' fully retracted. Aisimilar stop, to. upward movement of rod73 is provided by piston 78. All that is needed therefore to assure a desired spacingbetween the curved surfaces77, 49, is. to fix the length of rod73 to providethis spacing when both pistons 68 and 78 are fully retracted.

Operation In considering in more detail the operation-of the appaa. ratus; movements of the apparatus subsequent to the-sposition shown in Figure 1 will be dealt with.. The. posi tions of the plate 51 and the support fixture 12. as shown in Figure 1, are those assumed immediately after termination of an intermitetnt movement of turntable. 10; At

this portion of the cycle of operation, the cam follower:89: engages a riser portion of cam 87 and is moving upwardly. thereon. The valve 92 has-not yet been opened, so that track 15 that is normal to the axis of shaft 22 throughout" an arc of rotation of shaft 22. -of270, which serves to: hold-the turntable from rotation. Suchcontinued rotation of shaft 22 through the aforementioned are also causes the cam 87 to rotate to cause the cam follower89 to move to the upper dwell of the cam which may extend;

through an arc of about 200. Such movement of the cam follower rotates lever 88 causing its downwardly 6X tending portion 911} to press down to open valve- 921 When thevalve 92 is opened piston 68 becomesextended; rotating the yoke 55 until the screw 71 abuts against the. stop member 72. Such rotation transmits adownwardt force on the inner sleeve 42 through the/shoes 57, 58 engaging a-shoulder of this sleeve. This forceresultsin a downward movement of the inner sleeve.42. andthe lever member 23. mounted thereon.v The. magnitudeof.

Thus, the vertical-position of bracket35 on rod 36 is adjusted. bymeans of. clamp 37 to'position. This; assures desiredclearance even though the lengthofleads.

this downward movement, by virtue of the adjustment aforementioned of screw 71, is about one quarter inch. This movement is sufiicient to cause the underside of plate 51 to engage the free ends of leads 27 in spite of the aforementioned tolerable variation in lead length. During such engagement, the lever 23 is free from restraint by rod 73 and consequently is rotated clockwise to the position shown in Figure 5.

As the yoke 55 is rotated to impart downward movement to sleeve 42 and lever 23, the pin 62 and the lever 56 are also caused to rotate, bringing the screw 93 into engagement with lever 100 and moving this lever against valve pin 102. This opens valve 103 causing the piston 78 and the rod 73 fixed thereto to move downwardly. Due to the actions of flow control valves 106 and 107 the actuations of pistons 68 and 78 is restrained to provide relatively smooth movements thereof. This restraint assures a complete downward movement of sleeve 42 and lever member 23 to floatingly engage the leads 27 before the rod 73 is impelled downwardly. Downward movement of the rod causes its lower curved surface 77 to engage the upper curved surface 49 of the shank 43 to first lock the lever 23 against rotation and then to move the assembly including the lever 23 and the inner sleeve 42 downwardly a distance of about 50 mils which is determined by the spacing between the nut 86 and the shoes 57, 58. This causes the leads 27 and the glass disc 26 through which they extend, to be moved downwardly about 50 mils. This magnitude of movement is permitted by a softened condition of the contacting portions of the disc and the envelope 24, produced by burner 29 at this station and similar burners at preceeding work stations, and is necessary for a good seal.

During the foregoing push-down operation, the support fixture 12 is rotated by belt 31, to uniformly heat the periphery of the region to be sealed.

The foregoing operations of the apparatus take place during rotation of shaft 22 through the aforementioned arc of 270 and during which the turntable 10 is stationary. Further rotation of shaft 22, causes the pin 19 to enter the portion of track 15 that has a component extending axially of the shaft, and causes the cam follower 89 to engage a fall on cam 87. As a consequence, the outwardly urged valve pin 91 is free to move to extended position thereby closing valve 92. This dcenergizes the cylinders 69 and 81 permitting the piston 68 to retract in response to the force of expansion spring 43, and the piston 78 to retract in response to the force of compression springs 84, 85. The aforementioned actions result in a raising of lever member 23 to its initial position to permit a succeeding support fixture and work pieces carried thereby to be brought to a position directly below the plate 51 of the lever.

The curvature in end surface 77 of rod 73 and the upper surface 49 of shank 48 are advantageous in that they permit a maximum area of contact between the rod 73 and lever 23 for locking the lever 23 against rotation immediately onengagement between the two surfaces mentioned. The curvatures are also advantageous in that they permit the aforementioned engagement to take place as a consequence of the same downward displacement of rod 73, in spite of variations in angular position of the lever 23. The curved surfaces referred to are kept in desired orientation angularly by means of pin 74 to permit the aforementioned contact therebetween.

It will be seen from the foregoing that an advantageous sealing apparatus is provided that contributes to the formation of an improved seal. While the push-down device described is particularly desirable in a sealing apparatus, it will be appreciated that it may find utility independently of such apparatus.

What is claimed is:

1. A sealing apparatus comprising a movable member, a movable support, a first power transfer means connected to said movable support for intermittently moving said support in a path below and crossing the vertical axis of said member, a second power transfer means connected to said member for yieldingly lowering said member toward said support, a third power transfer means movable to engage said member for first locking said member against yielding movement and then pushing said member downwardly a predetermined distance while locked against yielding movement, and an actuating means connected to said second and third power transfer means, said first power transfer means having a structure for holding said support stationary during an interval between two intermittent movements thereof and directly below said member, said actuating means being connected to said first power transfer means for actuating said second and third power transfer means only during said interval, said support being adapted to support softened work pieces in a vertical array, whereby said member is adapted to engage the upper of said work pieces and to push it downwardly through said predetermined distance for an improved seal.

2. A sealing apparatus comprising movable means adapted to support glass work pieces to be sealed, a first power transfer means connected to said movable means for intermittently moving said movable means in a predetermined path, whereby said movable means and said work pieces are momentarily stationary at a predetermined position in said path, means adjacent said position adapted to heat said work pieces to soften a portion thereof, a movable member adjacent said position, a second power transfer means connected to said member for moving said member into a yielding engagement with one of said work pieces, a third power transfer means movable to first engage said member to convert said yielding engagement to a non-yielding engagement and then to move said member forcefully against said one of said work pieces, an actuating means connected to said second and third power transfer means, and a shaft connecting said first power transfer means to said actuating means, for actuating said second power transfer means only when said movable means is stationary.

3. A sealing apparatus comprising a first member movable only in a vertical path, a second member movably mounted on a lower portion of said first member, a support adapted to support two work pieces in a vertical array, a first power transfer means connected to said support for moving said support to a position directly below said second member, a second power transfer means connected to said first movable member for lowering said first and second members, whereby said second memher is adapted to engage and respond in movement to the topmost of said work pieces, a third member movable in said path, a third power transfer means connected to said third member for moving said third member downwardly in said path for first engaging and locking said second member against movement in relation to said first member and then for lowering said first and second members a predetermined distance, whereby said work pieces are urged together for a good seal, actuating means connected to said second and third power transfer means, and a shaft fixed to said first power transfer means and to said actuating means for actuating said second and third power transfer means and deactuating said first power transfer means when said support is in said position.

4. A sealing apparatus comprising a movable support fixture, means for moving said support fixture intermittently in a predetermined path, whereby said fixture is successively stationary momentarily in a plurality of spaced positions in said path; means adjacent one of said positions adapted to heat to scaling softness work pieces supported in superposed relation on said support; a pushdown device adjacent said one of said positions, said push-down device including a member adapted to engage the topmost of said work pieces, a vertically movable support for said member, said member being pivoted manners? movable for loweringsaid support a predetermined distanceto cause said memberto engagezth'e:topmostiof'saidworkpiecesrand tol bexrotatedfthereby onsaid axis through a relatively small are, and means for simultaneously lockingsa-idm'emben againstrotation on said axis and low ering said -support another predetermined' di'stance to cause 1 said member to push downsaid topmost of said work' piece said another predetermined -distance for a good seal between said work pieces; said -lastnamed means including a'n' a'ctuatingmember in the p'ath-of movement of said lever said means for lowering "being actuated only'when said support fixture is stationary-in said-one of said posit-ions:

5; A'sealing apparatus comprising in combination: a

support fixture-adapted to support two glasswork pieces in superposed relation;- a first power transfer means con-- nected-to said fixture for'movin'g sai-d fixture intermittently in= a predetermined-path, whereby said' fixture is stationary irr'spaced portions of said path; means adjacent oneof said portions for heating a=contacting region of said work pieces to softness for sealing; a push-down device supported. above said oneof said portions and having a member movable pivotally on'a' horizontal axis and in a straightpath vertically; a second power transfer means connected to said member and first movingxsaid member downwardly a predetermined distance'to contact and be pivoted by the uppermost of said work pieces, and a third power transfer means for simultaneously locking said member. againstpivotal movement and moving the locked member downwardly another predetermined distance for pressing said work pieces together; said first power transfer means holding said fixture stationary in said one of said positions during actuation of said second and third power transfer means.

6. A sealing apparatus comprising in combination: a movable support fixture adapted to support two softened glass Work pieces in superposed relation; a pushdown device including a vertically movable hollow support and a member movably mounted on said support for vertical deflection; a first means including a shaft connected to said fixture for moving the same; a second means connected to said vertically movable support for moving the same downwardly a predetermined distance to cause said member to engage the topmost of said work pieces; a third means movable vertically in said hollow support for engaging said member and simultaneously restraining said member from deflection and moving said support and member downwardly another predetermined distance, whereby said softened glass work pieces are pushed together for a good seal therebetween; and an actuating means connected to said shaft and to said second means for deactivating said first means during actuation of said second means.

7. In a sealing apparatus, a support fixture adapted to support two glass work pieces, means adjacent said fixturefor heating contacting portions of said work pieces to plastic state, and a device adjacent said fixture and adapted to push said work pieces together to form a good seal therebetween, said device including a support mounted for movement toward said fixture, a member mounted pivotally on said support for pivotal deflection when said support is moved in one direction toward said fixture, means for moving said support a predetermined distance in said direction, and means for simultaneously restraining pivotal deflection of said member and moving said support further in said direction through another predetermined distance, whereby said member is adjustable to accommodate work pieces of different dimensions.

8. In combination, movable means adapted to support two glass work pieces in contacting relation; a first means including a shaft for intermittently moving said movable means in a predetermined path; means adjacent a portion of said path for heating the contacting reformovingsaidmembertoward said-portion ofsaid path for yieldinglyengaging one of said Work pieces-0n saidsupport-when said support is moved to said portion of the path, and a third meanshaving a movable member extending in said path responsive to movement'ofsaid'= second means for simultaneously restraining floating movements of said member and moving said' member against said one of saidwork pieces for compressing said contacting region; and an actuating means connected to said'shaft'and saidsecond means for actuating said sec-- ond means only between intermittent movements of said movable means.

9. A pushing device adapted to'push a predetermined distance in one'dlrecti'on" a work piece havinga random' dimension in said: direction, said" device comprise ing aisleeve'mounted" for movement in said direction, a work engaging member "mounted? adjacent one end of said sleevefor pivotal movement" on an axis normal .to' said direction, means for moving said sleeve in said direction to cause s-aid member to engage said work piece. and to 'be pivotallydefi'ected thereby, said means including atmembe-r movable in a predetermined path', and' means including a movable member in said path and 'responsive to said means for moving for restraining pivotal movement of said member and for moving, said sleeve andmemberwhile so restrainedsaid predetermined distance in said direction.

10. A pushing device comprising a longitudinally movable elongated sleeve, a work engaging member mounted at an end portion of said sleeve for pivotal movement on an axis normal to said sleeve, a rod longitudinally movable in said sleeve, said rod having a cylindrically curved concave end surface, said member having a cylindrically curved surface, the radii of curvature of said surfaces being substantially the same, means for moving said sleeve longitudinally in one direction with said end portion leading, for causing said member'to yieldingly engage a work piece having a random dimension in said. direction, means for moving said rod longitudinally in said direction for causing said end surface of said rod to engage said curved surface of said member, and means: engaging said rod and sleeve to restrain relative axial ro-- tation thereof, whereby said surfaces provide contacting; regions of relatively large area for effectively restraining. pivotal movement of said member during a subsequent thrust by said rod on said member.

11. A contact responsive thrust device comprising a support movable in a rectilinear path, a feeler member mounted on said support for pivotal movement on an: axis normal to said path, a combined locking and thrust member movable in said path for first locking said feeler member against said pivotal movement and then for moving said feeler member in said path, movable means connected to said support for moving said support and said feeler member a predetermined distance in one direc-- tion in said path, whereby said feeler member is adapted to engage a surface to which a thrust is to be given and to be pivoted on said axis by engagement with said surface, and means extending into the path of movement of said movable means for actuation thereby and connected to said thrust member for first moving saidthrust member to engage said feeler member and to first restrain further pivotal movement of said feeler member and then to move said thrust member another predetermined distance in said one direction, whereby said feeler member is: moved said another predetermined distance after engaging said surface for moving said surface said another predetermined distance.

12. A contact responsive thrust device according to claim 11, and wherein said feeler member has an arcuately curved surface, the center of curvature of said surface 1 comprising'said axis, and said thrust member has an arcuately curved surface, said .last named surface having a curvature similar to the curvature of said firstnamed surface, said arcuately curved surface of said feeler member having a larger dimension in the direction of curvature than said arcuately curved surface of said thrust member, whereby said arcuately curved surface of said thrust member is substantiallylentirely engaged by a portion of the curved surface of said feeler member for effectively restraining said feeler member from pivotal movement during the movement of said thrust member through said another predetermined distance.

13. A contact responsive device according to claim 11, and wherein said feeler member has a first surface having an arcuate curvature determined by a radius extending from said first surface to said axis, and said thrust member has a second surface curved similarly to and in the same direction as said first surface, said surfaces being of unequal length in the direction of curvature thereof, whereby said thrust member engages said feeler member in a relatively large area of contact when said thrust member is moved to engage said feeler member.

14. A sealing apparatus comprising a movable support fixture adapted to support a work piece to be sealed, 3. first means connected to said fixture for moving the same to a predetermined position, a thrust device adjacent said position, said device including a sleeve movable in a path extending toward said fixture in said position, a feeler lever mounted on said sleeve at an end thereof adjacent said position for pivotal movement on an axis normal to said path, a thrust rod movable longitudinally in said slceve, said feeler lever having a shank extending into said sleeve, said shank having an arcuately curved free end surface, said axis constituting the center of curvature of said surface, said thrust rod having a free end surface adjacent said shank surface, and curved similarly to said shank surface and in the same direction, a second means having a movable member for moving said sleeve and said feeler lever a predetermined distance toward said fixture in said position, whereby said feeler lever is adapted to engage said work piece and to be pivoted on said axis, and a third means extending into the path of movement of said movable member and responsive to said movable member for first causing said free end surface thereof to engage said shank surface for restraining pivotal movement of said feeler lever and then causing said rod to move another predetermined distance toward said fiixture, whereby said feeler lever is adapted to apply a thrust to said work piece through said another predetermined distance, said shank surface being longer in the direction of curvature thereof than said thrust rod surface, whereby said surfaces have relatively large areas thereof in contact in any one of a plurality of different positions to which said feeler lever is pivoted for effective restraint of pivotal movement of said lever.

References Cited in the file of this patent UNITED STATES PATENTS 2,153,370 Donovan Apr. 4, 1939 2,361,517 White Oct. 31, 1944 FOREIGN PATENTS 16,005 Great Britain 1889 

